Over the last few decades, decorative extruded thermoplastic articles have gained wide consumer acceptance in place of natural wood and metal or manufactured as a components of wood, metal or textile-based articles. Typical decorative trims comprise elongated, extruded profiles or sheets. The applications for these extrudates have been exploited in three principal commercial areas, namely interior and exterior construction, and automotive. Exterior construction components include siding, soffit, window exterior panels and trim pieces, and patio furniture. Interior uses include furniture, office partitions, window trim, wall panels, wall trim pieces and ceiling panel assemblies.
Interior vertical window blinds comprise narrow elongated slats which are arranged to overlap slightly and rotated in unison to adjust the light or view through the window opening. The slats are made from a variety of materials such as aluminum or extruded vinyl strips and are optionally decorated by attaching webs, paint or narrow woven fabrics. Vertical slat assemblies can be designed with decorative features such as combinations of a slat member and a decorative film attached thereupon to the face, back or both sides. The vertical louver described in U.S. Pat. No. 4,049,038('038) comprises lateral inwardly facing attachment means which are flanges for receiving an insert such as a strip of wallpaper or fabric. U.S. Pat. No. 4,628,980('980) discloses a louver of identical shape to '038 but incorporates co-extruded transparent flanges. U.S. Pat. No. 4,195,680 discloses decorative attachments to an '038 flanged louver comprising one or more multiple clear or translucent tinted film inserts which allow convenient color changes.
U.S. Pat. No. 4,877,077 ('077) discloses a vertical louver made from co-extruded vinyl thermoplastic wherein a transparent outer layer containing a pearlescent pigment is co-extruded with an opaque base layer. The opaque base layer is visible and reflects light through the pearlescent surface layer. Optionally, a transparent or translucent tinting color dye is incorporated in the outer layer. An opacified pearlescent louver is disclosed in U.S. Pat. No. 5,194,209.
The use of metallic powders as dispersions in polymeric liquids for simulating weathered copper is disclosed in U.S. Pat. No. 4,416,940. A base coat-top coat method is taught wherein a patina-color is applied in a base coat followed by top coating with copper colored, coated mica. The greenish patina with the overlying pearlescent mica provides an appearance of weathered copper, a simulation of the aged elemental metal but which does not change shades as the metal does. The liquid film forming binders taught in '940 include thermosetting vinyls, halogenated vinyls, polyhalogenated vinyls, styrenes, acrylics, polyesters, urethanes, and mixtures.
The use of metallic pigments is prominent in automotive finishes and trim pieces. Color matching of trim pieces to the body panel is achieved by the use of colored plasticized PVC films which may be laminated over a substrate. These flexible films are also coextruded with other base compounds for economical savings by utilizing small amounts of metallic or pearlescent pigments only in the thin outer flexible skin.
A decorative film on a thermoplastic core strip is disclosed for automotive trim strips in U.S. Pat. No. 4,978,490. A solid non-weatherable PVC is suggested for the thermoplastic core. The outer layer is injection molded thermoplastic and molded with the core placed within the mold. The gist of '490 is the shaping and cutting of the core piece to less than a predetermined length, separately forming end pieces, and molding the outer appearance layer.
There are dispersion and settling problems attendant in the use of powdered metal flakes for paints. The pearlescent pigments have been used in paints, in place of metallic pigments. U.S. Pat. No. 4,551,491 teaches a base coat-clear coat in which an iron oxide treated mica is contained in the base coat. The base coat is overcoated with a transparent thermoplastic or thermosetting liquid resin. These metal powders are suitable for use with low viscosity plasticized PVC, PVC plastisol or paint vehicles but present unique problems when one attempts their use in a rigid, thermoplastic PVC matrix.
Contrasted with the paint methods and flexible thermoplastics employing metallic powder where only low shear forces exist, rigid thermoplastic resins flow only under heat and pressure wherein high shear forces develop. Metallic pigments are fragile and break down readily under high shear forces. Improved spheroidal shaped aluminum powder in certain instances may withstand the shearing action when dispersed in a thermoplastic resin under melt-flow conditions.
The various decorative thermoplastic louvers of the prior art have the appearance of colored plastic or pearlescence. It would be desirable to obtain an appearance for a rigid thermoplastic louver which simulates a buffed or polished metal look. In the thermoplastic extrusion of louvers from rigid polyvinyl chloride compound containing of aluminum fine particles it has been observed that the hot, viscous PVC extrusion readily smokes or ignites as it exits the extruder die, since aluminum metal powder is flammable. Moreover, in the use of aluminum particles, certain sized particles tend to plug in-line extrusion filter packs causing interruption of continuous processing. It would be desirable to achieve continuous manufacture of rigid louver profiles having the look of polished metal without the hazards due to burning under high shear.